The present invention relates to a roller-hearth continuous furnace used for ceramic firing for production of household or industrial ceramic wares.
When ceramic firing must be conducted in a non-oxidizing atmosphere for production of household or industrial ceramic wares, there have been mainly used single furnaces of electrical heating type. Recently, however, use of continuous furnace such as roller-hearth furnace of gas heating type has been investigated in order to improve the productivity and economy of said single furnaces.
When a roller-hearth continuous furnace is used for ceramic firing for production of, for example, ceramic wares requiring controlled atmosphere firing, gas burners are allowed to produce reducing flames in the firing section, whereby the firing section, etc. inside the furnace are kept in a reducing atmosphere. In this furnace, however, even slight variation in said flames invites variation in furnace inside pressure or in boundary between reducing atmosphere and oxidizing atmosphere; hence, this tends to give fired products of nonuniform quality especially when the firing and quenching steps (these two steps have a large influence on the color development, etc. of fired products) must be conducted in a stable atmosphere.
Therefore, the object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and provide a roller-hearth continuous furnace of gas heating type, capable of conducting the cooling step in a stable atmosphere.